Stereo images with comfortable perceived depth

1. A method of producing a stereo image of a (real or simulated) scene using at least one (real or simulated) camera, which creates the impression of being a 3D image when viewed on a display by a user, wherein in each position at which an image is captured the camera axis is parallel to the camera axis at all other positions, and the depth of the scene is mapped onto a maximum perceived depth of the image on the display, and the maximum perceived depth is chosen to provide comfortable viewing for the user, wherein the method makes use of parameters of the display, including the maximum perceived depth of an object in front of the display N, and the maximum perceived depth of an object behind the display F, and also makes use of the user's eye separation E, and the distance Z of the viewer from the display.

2. A method as claimed in claim 1 , wherein the distance Z from the camera to the Zero Disparity Plane is calculated based on the values of N and F, and also on the values of the distance N from the camera to the closest surface in the scene, and the distance F from the camera to the furthest surface in the scene.

3. A method as claimed in claim 1 , wherein the distance Z from the camera to the Zero Disparity Plane is specified, values of the distance N from the camera to the closest surface in the scene is specified, values of the distance F from the camera to the furthest surface in the scene is specified, and the most suitable of N or F is kept fixed and a new value is calculated for the other of N or F based on the values of N and F.

4. A method as claimed in claim 1 , wherein any one of the distance N from the camera to the closest surface in the scene, the distance F from the camera to the furthest surface in the scene, and the distance Z from the camera to the Zero Disparity Plane is calculated based on the values of the other two.

5. A method as claimed in claim 1 , wherein the maximum crossed and uncrossed disparities d N and d F , are calculated from N, F, the separation E of the user's eyes, and the distance Z from the user to the display.

6. A method as claimed in claim 1 , wherein the camera separation A used to produce the stereo image is calculated based on N and F to achieve the desired perceived depth (N F).

7. A method as claimed in claim 6 , wherein the field of view of the camera is adjusted to allow for that part of the image which will be cropped as a result of the use of parallel camera positions.

8. A method as claimed in claim 1 , wherein the camera separation is fixed, and the desired focal length of the camera is calculated to achieve the desired perceived depth (N F).

9. A method as claimed in claim 1 , wherein the distance from the camera to the closest surface in the scene is a value of N and the distance from the camera to the furthest surface in the scene is a value of F , the value of N and F are specified, and wherein the most suitable of N or F is kept fixed, and the focal length f of the camera is taken into account when measuring the values of N and F .

10. A method as claimed in claim 1 , wherein the camera separation A is limited to the user's eye separation E multiplied by the scale factor S as herein defined.

11. A method as claimed in claim 1 , wherein a stereoscopic pair of images is created using a given camera separation, the images are analysed to find the disparities between homologous points in the images, and said disparities are then used to adjust said camera separation.

12. A method as claimed in claim 11 , wherein said stereoscopic pair of images is created for display on a first display, and wherein said camera separation is adjusted to make the images suitable for display on a second display.

13. A computing device adapted to carry out a method as claimed in claim 1 .

14. A camera comprising a computing device as claimed in claim 13 .

15. A camera system comprising a computing device as claimed in claim 13 .